The objectives of this research are threefold. First it is intended to do a series of experiments on various aspects of the pathogenesis of hypertension. These include studies on the role of intravascular coagulation in the transition from the benign to the malignant phase of experimental hypertension in the rabbit and rat, and the prevention of development of malignant hypertension by anticoagulants. The effects of sudden loss of sodium will be studied in the transition from benign to malignant phases. Finally in this part studies will be made on the differences between one- and two-kidney clip hypertension in the rat using an atubular kidney preparation. Second, the thesis of greater degrees of arterial damage being present in high renin hypertension that in low renin hypertension will be tested experimentally in the rat. Vascular damage will be assessed by tracer techniques, scanning and transmission electron microscopy, and by autoradiography to study endothelial cell turnover. Third, a scanning electron microscope study will be made of a histologically appropriate model of acute renal failure in the rabbit. The effects of clonidine and of reno-medullary implants will also be explored.